Diminazene aceturate attenuates systemic inflammation via microbiota gut-5-HT brain-spleen sympathetic axis in male mice.

The sympathetic arm of the inflammatory reflex is the efferent pathway through which the central nervous system (CNS) can control peripheral immune responses. Diminazene aceturate (DIZE) is an antiparasitic drug that has been reported to exert protective effects on various experimental models of inflammation. However, the pathways by which DIZE promotes a protective immunomodulatory effects still need to be well established, and no studies demonstrate the capacity of DIZE to modulate a neural reflex to control inflammation. C57BL/6 male mice received intraperitoneal administration of DIZE (2 mg/Kg) followed by lipopolysaccharide (LPS, 5 mg/Kg, i.p.). Endotoxemic animals showed hyperresponsiveness to inflammatory signals, while those treated with DIZE promoted the activation of the inflammatory reflex to attenuate the inflammatory response during endotoxemia. The unilateral cervical vagotomy did not affect the anti-inflammatory effect of DIZE in the spleen and serum. At the same time, splenic denervation attenuated tumor necrosis factor (TNF) synthesis in the spleen and serum. Using broad-spectrum antibiotics for two weeks showed that LPS modulated the microbiota to induce a pro-inflammatory profile in the intestine and reduced the serum concentration of tryptophan and serotonin (5-HT), while DIZE restored serum tryptophan and increased the hypothalamic 5-HT levels. Furthermore, the treatment with 4-Chloro-DL-phenylalanine (pcpa, an inhibitor of 5-HT synthesis) abolished the anti-inflammatory effects of the DIZE in the spleen. Our results indicate that DIZE promotes microbiota modulation to increase central 5-HT levels and activates the efferent sympathetic arm of the inflammatory reflex to control splenic TNF production in endotoxemic mice.

Therapeutic potential of psychedelics: History, advancements, and unexplored frontiers.

Psychedelics (serotonergic hallucinogens) are psychoactive substances that can alter perception and mood, and affect cognitive functions. These substances activate 5-HT2A receptors and may exert therapeutic effects. Some of the disorders for which psychedelic-assisted therapy have been studied include depression, addiction, anxiety and post-traumatic stress disorder. Despite the increasing number of studies reporting clinical effectiveness, with fewer negative symptoms and, additionally, minimal side effects, questions remain to be explored in the field of psychedelic medicine. Although progress has been achieved, there is still little understanding of the relationship among human brain and the modulation induced by these drugs. The present article aimed to describe, review and highlight the most promising findings in the literature regarding the (putative) therapeutic effects of psychedelics.

Non-invasive evaluation of vascular permeability in formalin-induced orofacial pain model using infrared thermography.

Enhanced vascular permeability at the site of injury is a prominent feature in acute inflammatory pain models, commonly assessed through the Evans Blue test. However, this invasive test requires euthanasia, thereby precluding further investigations on the same animal. Due to these limitations, the integration of non-invasive tools such as IRT has been sought. Here, we aimed to evaluate the use of thermography in a common orofacial pain model that employs formalin as a chemical irritant to induce local orofacial inflammation. Male Hannover rats (290-300 g, N = 43) were used. In the first approach, radiometric images were taken before and after formalin administration, assessing temperature changes and extravasated Evans Blue. The second approach included capturing pre- and post-formalin test radiometric images, followed by cytokine measurements in excised vibrissae tissue. Rats were anesthetized for vibrissae tissue collection, allowing correlations between thermographic patterns, nocifensive behavior duration, and cytokine levels in this area. Our findings revealed a positive correlation between local temperature, measured via thermography, and vascular permeability in the contralateral (r2 = 0.3483) and ipsilateral (r2 = 0.4502) side, measured using spectrophotometry. The obtained data supports the notion that thermography-based temperature assessment can effectively evaluate vascular permeability in the orofacial region.

Leptin signaling in the dorsomedial hypothalamus couples breathing and metabolism in obesity.

Mismatch between CO2 production (Vco2) and respiration underlies the pathogenesis of obesity hypoventilation. Leptin-mediated CNS pathways stimulate both metabolism and breathing, but interactions between these functions remain elusive. We hypothesized that LEPRb+ neurons of the dorsomedial hypothalamus (DMH) regulate metabolism and breathing in obesity. In diet-induced obese LeprbCre mice, chemogenetic activation of LEPRb+ DMH neurons increases minute ventilation (Ve) during sleep, the hypercapnic ventilatory response, Vco2, and Ve/Vco2, indicating that breathing is stimulated out of proportion to metabolism. The effects of chemogenetic activation are abolished by a serotonin blocker. Optogenetic stimulation of the LEPRb+ DMH neurons evokes excitatory postsynaptic currents in downstream serotonergic neurons of the dorsal raphe (DR). Administration of retrograde AAV harboring Cre-dependent caspase to the DR deletes LEPRb+ DMH neurons and abolishes metabolic and respiratory responses to leptin. These findings indicate that LEPRb+ DMH neurons match breathing to metabolism through serotonergic pathways to prevent obesity-induced hypoventilation.

Inhaled molecular hydrogen reduces hippocampal neuroinflammation, glial reactivity and ameliorates memory impairment during systemic inflammation.

Sepsis is associated with numerous physiological and biochemical abnormalities that result in a life-threatening condition. The involvement of the Central Nervous System (CNS) during sepsis has received considerable attention, especially the hippocampus which plays a key role in the learning and memory processes. The increased interest in this limbic region during systemic inflammation (SI) is related to the number of sepsis survivor patients who have cognitive impairments. A single injection of lipopolysaccharide (LPS)-induced systemic inflammation is the most commonly used murine endotoxemia model because it replicates several pathophysiological changes observed in severe sepsis. Molecular hydrogen (H2) has been used as an anti-inflammatory therapeutic strategy to prevent neuroinflammation. However, the mechanisms by which inhaled H2 mitigate memory loss during SI remains unknown. To understand how H2 acts in the hippocampus, the current study focused on specific mechanisms that may be involved in reducing neuroinflammation in rats during SI. We hypothesized that inhaled H2 decreases LPS-induced hippocampal pro-inflammatory cytokines surges and this effect is associated with reduced memory loss. Using different and integrative approaches, i.e., from hippocampal cells electrophysiology to animal behavior, we report that inhaled H2 decreased LPS-induced peripheral and hippocampal inflammation, decreased microglial and astrocytic activation, lessen memory loss without affecting long-term potentiation (LTP). To our knowledge, this is the first evidence showing that inhaled H2 reduces hippocampal microglial and glial cells inflammation, which may be associated with a reduced memory impairment induced by SI.

Orofacial anti-hypernociceptive effect of citral in acute and persistent inflammatory models in rats.

Orofacial pain has significant psychological and physiological effects. Citral (3,7-dimethyl-2,6-octadienal) is the main component of Cymbopogon citratus (DC) Stapf, an herb with analgesic properties. Although citral has been considered a potent analgesic, its putative effects on orofacial pain are still unknown. OBJECTIVE: The objective of this study is to test the hypothesis that citral modulates orofacial pain using two experimental models: formalin-induced hyperalgesia in the vibrissae area and during persistent temporomandibular hypernociception using Complete Freund's Adjuvant - CFA test. METHODS: For the formalin test, citral (100 and 300 mg/kg, oral gavage) or its vehicle (Tween 80, 1 %) were given 1 h before the formalin injection subcutaneously (sc) into the vibrissae area. For the CFA model, we analyzed the prophylactic (100 mg/kg of citral by oral gavage, 1 h before CFA injection) and the chronic therapeutic (citral treatment 1-hour post-CFA injection and daily post-CFA injection) effect of citral or its vehicle in animals treated with CFA for 8 days. RESULTS: Citral caused a decrease in formalin-induced local inflammation and the time spent performing nociceptive behavior in a dose-dependent fashion. Similarly, prophylactic and therapeutic citral treatment decreased the CFA-induced persistent mechanical hypernociception in the temporomandibular area. CONCLUSION: Our data strengthen the notion that citral plays a powerful antinociceptive role by decreasing orofacial hypernociception in formalin and CFA models.

Effects of hydrogen gas inhalation on L-DOPA-induced dyskinesia.

L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia is a side effect of Parkinson's disease treatment and it is characterized by atypical involuntary movements. A link between neuroinflammation and L-DOPA-induced dyskinesia has been documented. Hydrogen gas (H2) has neuroprotective effects in Parkinson's disease models and has a major anti-inflammatory effect. Our objective is to test the hypothesis that H2 inhalation reduces L-DOPA-induced dyskinesia. 15 days after 6-hydroxydopamine lesions of dopaminergic neurons were made (microinjection into the medial forebrain bundle), chronic L-DOPA treatment (15 days) was performed. Rats were exposed to H2 (2% gas mixture, 1 h) or air (controls) before L-DOPA injection. Abnormal involuntary movements and locomotor activity were conducted. Striatal microglia and astrocyte was analyzed and striatal and plasma samples for cytokines evaluation were collected after the abnormal involuntary movements analysis. H2 inhalation attenuated L-DOPA-induced dyskinesia. The gas therapy did not impair the improvement of locomotor activity achieved by L-DOPA treatment. H2 inhalation reduced activated microglia in the lesioned striatum, which is consistent with the observed reduced pro-inflammatory cytokines levels. Display of abnormal involuntary movements was positively correlated with plasma IL-1ß and striatal TNF-α levels and negatively correlated with striatal IL-10 levels. Prophylactic H2 inhalation decreases abnormal involuntary movements in a preclinical L-DOPA-induced dyskinesia model. The H2 antidyskinetic effect was associated with decreased striatal and peripheral inflammation. This finding has a translational importance to L-DOPA-treated parkinsonian patients' well-being.

CORM-401, an orally active carbon monoxide-releasing molecule, increases body temperature by activating non-shivering thermogenesis in rats.

Thermoregulation is critical in health and disease and is tightly controlled to maintain body temperature homeostasis. Carbon monoxide (CO), an endogenous gasotransmitter produced during heme degradation by heme oxygenases, has been suggested to play a role in body core temperature (Tb) regulation. However, a direct involvement of CO in thermoregulation has not been confirmed and its mechanism(s) of action remain largely unknown. In the present study we characterized the effects of systemic delivery of CO by administration of an orally active CO-releasing molecule (CORM-401) on Tb regulation in conscious freely moving rats. Specifically, we evaluated the main thermo effectors in rats treated with CORM-401 by assessing: (i) non-shivering thermogenesis, i.e. the increased metabolism of brown fat measured through oxygen consumption and (ii) the rate of heat loss from the tail through calculations of heat loss index. We found that oral administration of CORM-401 (30 mg/kg) resulted in augmented CO delivery into the blood circulation as evidenced a by significant increase in carbon monoxy hemoglobin levels(COHb). In addition, treatment with CORM-401 increased Tb, which was caused by an elevated non-shivering thermogenesis indicated by increased oxygen consumption without significant changes in the tail heat loss. On the other hand, CORM-401 did not affect blood pressure, but significantly decreased heart rate. In summary, the findings of the present study reveal that increased circulating CO levels lead to a rise in Tb, which could have important implications in the emerging role of CO in the modulation of energetic metabolism.

Chronic rapamycin treatment decreases hepatic IL-6 protein, but increases autophagy markers as a protective effect against the overtraining-induced tissue damage.

Regular endurance exercise is a non-pharmacological strategy to protect the liver against diseases. Conversely, exercise may be harmful when excessive, the so-called overtraining. As expected, mice who underwent an overtraining protocol presented higher levels of proinflammatory cytokines in the serum and liver. Based on the relationship among overtraining, inflammation and mammalian target of rapamycin complex 1 (mTORC1) upregulation, the present study verified if animals submitted to an overtraining protocol, but with inhibition of the mTOR pathway via rapamycin injections could mitigate the liver and serum inflammation. Once autophagy can be linked to the improvement of hepatic dysfunction, we also investigated if the inhibition of mTORC1 by rapamycin can improve hepatic autophagy. The animals were randomized into four groups: control (CT; sedentary mice), overtraining by downhill running (OT; mice submitted to the downhill running-based overtraining protocol), overtraining by downhill running with chronic administration of rapamycin (OT/Rapa; mice submitted to the downhill running-based overtraining protocol with intraperitoneal injections of rapamycin) and aerobic (AER; submitted to aerobic training protocol). The serum and liver of the animals were used for biochemical analysis, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunoblotting. The main results are (a) OT and OT/Rapa protocols decreased the performance; (b) the protein levels of interleukin 6 (IL-6) were higher for the OT group; the OT/Rapa group reduced the autophagic genes, increased the microtubule-associated protein light chain 3 II/I (LC3II/LC3I) protein ratio and decreased the sequestosome 1 (SQSTM1) protein. In conclusion, rapamycin appears efficiently to increase the autophagy proteins and decrease IL-6 protein in the liver of overtraining mice.

The effect of brain serotonin deficiency on breathing is magnified by age.

Serotonin is an important mediator modulating behavior, metabolism, sleep, control of breathing, and upper airway function, but the role of aging in serotonin-mediated effects has not been previously defined. Our study aimed to examine the effect of brain serotonin deficiency on breathing during sleep and metabolism in younger and older mice. We measured breathing during sleep, hypercapnic ventilatory response (HCVR), CO2 production (VCO2 ), and O2 consumption (VO2 ) in 16-18-week old and 40-44-week old mice with deficiency of tryptophan hydroxylase 2 (Tph2), which regulates serotonin synthesis specifically in neurons, compared to Tph2+/+ mice. As expected, aging decreased VCO2 and VO2 . Tph2 knockout resulted in an increase in both metabolic indexes and no interaction between age and the genotype was observed. During wakefulness, neither age nor genotype had an effect on minute ventilation. The genotype did not affect hypercapnic sensitivity in younger mice. During sleep, Tph2-/- mice showed significant decreases in maximal inspiratory flow in NREM sleep, respiratory rate, and oxyhemoglobin saturation in REM sleep, compared to wildtype, regardless of age. Neither serotonin deficiency nor aging affected the frequency of flow limited breaths (a marker of upper airway closure) or apneas. Serotonin deficiency increased the amount and efficiency of sleep only in older animals. In conclusion, younger Tph2-/- mice were able to defend their ventilation and phenotypically did not differ from wildtype during wakefulness. In contrast, both young and old Tph2-/- mice showed sleep-related hypoventilation, which was manifested by hypoxemia during REM sleep.

Autonomic Disbalance During Systemic Inflammation is Associated with Oxidative Stress Changes in Sepsis Survivor Rats.

Sepsis affects 31.5 million people worldwide. It is characterized by an intense drop in blood pressure driving to cardiovascular morbidity and mortality. Modern supportive care has increased survival in patients; however, after experiencing sepsis, several complications are observed, which may be potentiated by new inflammatory events. Nevertheless, the interplay between sepsis survivors and a new immune challenge in cardiovascular regulation has not been previously defined. We hypothesized that cecal ligation and puncture (CLP) cause persistent cardiovascular dysfunctions in rats as well as changes in autonomic-induced cardiovascular responses to lipopolysaccharide (LPS). Male Wistar rats had mean arterial pressure (MAP) and heart rate (HR) recorded before and after LPS or saline administration to control or CLP survivor rats. CLP survivor rats had similar baseline MAP and HR when compared to control. LPS caused a drop in MAP accompanied by tachycardia in control, while CLP survivor rats had a noteworthy enhanced MAP and a blunted tachycardia. LPS-induced hemodynamic changes were related to an autonomic disbalance to the heart and resistance vessels that were expressed as an increased low- and high-frequency power of pulse interval in CLP survivors after saline and enhancement in the low-frequency power of systolic arterial pressure in control rats after LPS. LPS-induced plasma interferon γ, but not interleukin-10 surges, was blunted in CLP survivor rats. To further access whether or not LPS-induced autonomic disbalance in CLP survivor rats was associated with oxidative stress dysregulation, superoxide dismutase (SOD) activity and thiobarbituric acid reactive substances (TBARS) plasma levels changes were measured. LPS-induced oxidative stress was higher in CLP survivor rats. These findings indicate that key changes in hemodynamic regulation of CLP survivors rats take place in response to LPS that are associated with oxidative stress changes, i.e., reduced SOD activity and increased TBARS levels.

Acute autonomic effects of rose oxide on cardiovascular parameters of Wistar and spontaneously hypertensive rats.

AIMS: Anti-inflammatory molecules, such as rose oxide (RO), are likely to exert therapeutic effects in systemic arterial hypertension (SAH), a disease associated with abnormal immune responses. We aimed to investigate acute autonomic effects of RO on hemodynamic parameters of Wistar and spontaneously hypertensive rats (SHR). METHODS: Rats were anesthetized and femoral artery and veins were cannulated. Next day, blood pressure (BP) and heart rate (HR) were recorded. Acute effects of RO (1.25, 2.5, or 5.0 mg/kg; iv) on BP, HR, and variability of systolic arterial pressure (SAP) and pulse interval (PI) were assessed. The effects of RO were also investigated in SHR, which received atropine (2 mg/kg), propranolol (4 mg/kg), or hexamethonium (20 mg/kg) 15 min before receiving RO. Vasorelaxant effects of RO (10-10 to 10-4 M) on aortic rings of rats were also assessed. KEY FINDINGS: In Wistar rats, none of the RO doses evoked significant changes in BP, HR, and variability of SAP and PI. On the other hand, in SHR, RO elicited reduction in mean arterial pressure (MAP), and prevented the increase in the low frequency power (LF) of the SAP spectra. Pretreatment with atropine or propranolol did not alter hypotension, but attenuated RO-induced bradycardia. Hexamethonium prevented RO-induced hypotension and bradycardia. RO exerted vasorelaxant effects on aortic rings with (Wistar and SHR) or without functional endothelium (SHR only). SIGNIFICANCE: Rose oxide, a monoterpene with anti-inflammatory properties, acts as an antihypertensive molecule due to its ability to acutely promote hypotension and bradycardia in spontaneously hypertensive rats.

The Effect of DREADD Activation of Leptin Receptor Positive Neurons in the Nucleus of the Solitary Tract on Sleep Disordered Breathing.

Obstructive sleep apnea (OSA) is recurrent obstruction of the upper airway due to the loss of upper airway muscle tone during sleep. OSA is highly prevalent, especially in obesity. There is no pharmacotherapy for OSA. Previous studies have demonstrated the role of leptin, an adipose-tissue-produced hormone, as a potent respiratory stimulant. Leptin signaling via a long functional isoform of leptin receptor, LEPRb, in the nucleus of the solitary tract (NTS), has been implicated in control of breathing. We hypothesized that leptin acts on LEPRb positive neurons in the NTS to increase ventilation and maintain upper airway patency during sleep in obese mice. We expressed designer receptors exclusively activated by designer drugs (DREADD) selectively in the LEPRb positive neurons of the NTS of Leprb-Cre-GFP mice with diet-induced obesity (DIO) and examined the effect of DREADD ligand, J60, on tongue muscle activity and breathing during sleep. J60 was a potent activator of LEPRb positive NTS neurons, but did not stimulate breathing or upper airway muscles during NREM and REM sleep. We conclude that, in DIO mice, the stimulating effects of leptin on breathing during sleep are independent of LEPRb signaling in the NTS.

Role of hydrogen sulfide in ventilatory responses to hypercapnia in the medullary raphe of adult rats.

NEW FINDINGS: What is the central question of this study? There is evidence that H2 S plays a role in the control of breathing: what are its actions on the ventilatory and thermoregulatory responses to hypercapnia via effects in the medullary raphe, a brainstem region that participates in the ventilatory adjustments to hypercapnia? What is the main finding and its importance? Hypercapnia increased the endogenous production of H2 S in the medullary raphe. Inhibition of endogenous H2 S attenuated the ventilatory response to hypercapnia in unanaesthetized rats, suggesting its excitatory action via the cystathionine ß-synthase-H2 S pathway in the medullary raphe. ABSTRACT: Hydrogen sulfide (H2 S) has been recently recognized as a gasotransmitter alongside carbon monoxide (CO) and nitric oxide (NO). H2 S seems to modulate the ventilatory and thermoregulatory responses to hypoxia and hypercapnia. However, the action of the H2 S in the medullary raphe (MR) on the ventilatory responses to hypercapnia remains to be elucidated. The present study aimed to assess the role of H2 S in the MR (a brainstem region that contains CO2 -sensitive cells and participates in the ventilatory adjustments to hypercapnia) in the ventilatory responses to hypercapnia in adult unanaesthetized Wistar rats. To do so, aminooxyacetic acid (AOA; a cystathionine ß-synthase (CBS) enzyme inhibitor), propargylglycine (PAG; a cystathionine γ-lyase enzyme inhibitor) and sodium sulfide (Na2 S; an H2 S donor) were microinjected into the MR. Respiratory frequency (fR ), tidal volume (VT ), ventilation ( V̇E ), oxygen consumption ( V̇O2 ) and body temperature (Tb ) were measured under normocapnic (room air) and hypercapnic (7% CO2 ) conditions. H2 S concentration within the MR was determined. Microinjection of the drugs did not affect fR , VT and V̇E during normocapnia when compared to the control group. However, the microinjection of AOA, but not PAG, attenuated fR and V̇E during hypercapnia in comparison to the vehicle group, but had no effects on Tb . In addition, we observed an increase in the endogenous production of H2 S in the MR during hypercapnia. Our findings indicate that endogenously produced H2 S in the MR plays an excitatory role in the ventilatory response to hypercapnia, acting through the CBS-H2 S pathway.

5-HT neurons of the medullary raphe contribute to respiratory control in toads.

Air-breathing vertebrates undergo respiratory adjustments when faced with disturbances in the gas composition of the environment. In mammals, the medullary raphe nuclei are involved in the neuronal pathway that mediates the ventilatory responses to hypoxia and hypercarbia. We investigate whether the serotoninergic neurons of the medullary raphe nuclei of toads (Rhinella diptycha) play a functional role in respiratory control during resting conditions (room air), hypercarbia (5% CO2), and hypoxia (5% O2). The raphe nuclei were located and identified based on the location of the serotoninergic neurons in the brainstem. We then lesioned the medullary raphe (raphe pallidus, obscurus and magnus) with anti-SERT-SAP and measured ventilation in both control and lesioned groups and we observed that serotonin (5-HT) specific chemical lesions of the medullary raphe caused reduced respiratory responses to both hypercarbia and hypoxia. In summary, we report that the serotoninergic neurons of the medullary raphe of the cururu toad Rhinella diptycha participate in the chemoreflex responses during hypercarbia and hypoxia, but not during resting conditions. This current evidence in anurans, together with the available data in mammals, brings insights to the evolution of brain sites, such as the medullary raphe, involved in the ventilatory chemoreflex in vertebrates.

Designer Receptors Exclusively Activated by Designer Drugs Approach to Treatment of Sleep-disordered Breathing.

Rationale: Obstructive sleep apnea is recurrent upper airway obstruction caused by a loss of upper airway muscle tone during sleep. The main goal of our study was to determine if designer receptors exclusively activated by designer drugs (DREADD) could be used to activate the genioglossus muscle as a potential novel treatment strategy for sleep apnea. We have previously shown that the prototypical DREADD ligand clozapine-N-oxide increased pharyngeal diameter in mice expressing DREADD in the hypoglossal nucleus. However, the need for direct brainstem viral injections and clozapine-N-oxide toxicity diminished translational potential of this approach, and breathing during sleep was not examined.Objectives: Here, we took advantage of our model of sleep-disordered breathing in diet-induced obese mice, retrograde properties of the adeno-associated virus serotype 9 (AAV9) viral vector, and the novel DREADD ligand J60.Methods: We administered AAV9-hSyn-hM3(Gq)-mCherry or control AAV9 into the genioglossus muscle of diet-induced obese mice and examined the effect of J60 on genioglossus activity, pharyngeal patency, and breathing during sleep.Measurements and Main Results: Compared with control, J60 increased genioglossus tonic activity by greater than sixfold and tongue uptake of 2-deoxy-2-[18F]fluoro-d-glucose by 1.5-fold. J60 increased pharyngeal patency and relieved upper airway obstruction during non-REM sleep.Conclusions: We conclude that following intralingual administration of AAV9-DREADD, J60 can activate the genioglossus muscle and improve pharyngeal patency and breathing during sleep.

Recent Advances in Molecular Hydrogen Research Reducing Exercise-Induced Oxidative Stress and Inflammation.

Physical exercise-induced oxidative stress and inflammation may be beneficial when exercise is a regular activity, but it is rather harmful when exercise is exhaustive and performed by unaccustomed organisms. Molecular hydrogen (H2) has recently appeared as a potent antioxidant and anti-inflammatory molecule in numerous pathological conditions. However, its role is relatively unknown under physiological conditions such as physical exercise. Therefore, this review summarizes the current knowledge of the H2, reducing oxidative stress and inflammation in physical exercise, reporting data from both animal and human studies.

Molecular hydrogen downregulates acute exhaustive exercise-induced skeletal muscle damage.

Physical exercise-induced skeletal muscle damage may be characterized by increased oxidative stress, inflammation, and apoptosis which may be beneficial when exercise is regular, but it is rather harmful when exercise is exhaustive and performed acutely by unaccustomed individuals. Molecular hydrogen (H2) has emerged as a potent antioxidant, anti-inflammatory, and anti-apoptotic agent, but its action on the deleterious effects of acute exhaustive exercise in muscle damage remain unknown. Therefore, we tested the hypothesis that H2 decreases acute exhaustive exercise-induced skeletal muscle damage of sedentary rats. Rats ran to exhaustion on a sealed treadmill inhaling an H2-containing mixture or the control gas. We measured oxidative stress (SOD, GSH, and TBARS), inflammatory (TNF-α, IL-1ß, IL-6, IL-10, and NF-κB phosphorylation), and apoptotic (expression of caspase-3, Bcl-2, and HSP70) markers. Exercise caused no changes in SOD activity but increased TBARS levels. H2 caused increases in exercise-induced SOD activity and blunted exercise-induced increased TBARS levels. We observed exercise-induced TNF-α and IL-6 surges as well as NF-κB phosphorylation, which were blunted by H2. Exercise increased cleaved caspase-3 expression, and H2 reduced this response. In conclusion, H2 effectively downregulates muscle damage, reducing oxidative stress, inflammation, and apoptosis after acute exhaustive exercise performed by an unaccustomed organism.

Hypothermic Effect of Acute Citral Treatment during LPS-induced Systemic Inflammation in Obese Mice: Reduction of Serum TNF-α and Leptin Levels.

Citral is a mixture of monoterpenes present in the essential oil of several plants, such as Cymbopogon citratus and Zingiber officinale, possessing anti-inflammatory, anti-ulcerogenic, and antipyretic actions. We investigated the action of citral on body temperature (Tb) and inflammatory signaling in eutrophic and obese mice during Systemic Inflammation (SI) induced by Lipopolysaccharide (LPS). Thus, we assessed the effect of citral (25, 100, and 300 mg/kg) and ibuprofen in LPS-induced SI in Swiss male mice fed a standard diet (SD) or high-fat diet (HFD) for 12 weeks. Following SI induction, we measured Tb and collected the serum, hypothalamus, and gastric mucosa for biochemical measurements. Acute treatment with citral decreased the Tb of both SD and HFD-fed animals. Citral (300 mg/kg) treatment caused a significantly lower Tb variation in HFD-fed animals than in those fed the SD. Citral reduced peripheral levels of tumor necrosis factor (TNF)-α in SD and HFD mice and decreased serum leptin concentration in HFD mice 90 min after the LPS challenge. Furthermore, citral also reduced interleukin (IL)-6 levels in the hypothalamus of obese mice. In summary, citral effectively reduced Tb during SI by reducing inflammatory mediators with a distinct action profile in HFD mice when compared with SD.

Can selective serotonin reuptake inhibitors have a neuroprotective effect during COVID-19?

The absence of a specific treatment for SARS-CoV-2 infection led to an intense global effort in order to find new therapeutic interventions and improve patient outcomes. One important feature of COVID-19 pathophysiology is the activation of immune cells, with consequent massive production and release of inflammatory mediators that may cause impairment of several organ functions, including the brain. In addition to its classical role as a neurotransmitter, serotonin (5-hydroxytryptamine, 5-HT) has immunomodulatory properties, downregulating the inflammatory response by central and peripheral mechanisms. In this review, we describe the roles of 5-HT in the regulation of systemic inflammation and the potential benefits of the use of specific serotonin reuptake inhibitors as a coadjutant therapy to attenuate neurological complications of COVID-19.